The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Steam cracking and residue fluid catalytic cracking are widely used to crack different crude oil fractions into olefins, preferably ethylene, propylene, butylene and naphtha. However byproducts such as pyrolysis oil, coke and clarified slurry oil may also be produced in these processes. Accordingly, several methods have been proposed in the prior art for upgrading these low value streams. For instance, US patent No. US20130233768A1 describes an integrated solvent deasphalting, hydrotreating and steam pyrolysis process for direct processing of a crude oil to produce petrochemicals, wherein pyrolysis oil is recovered as fuel oil. US patent No. US20080083649A1 describes a method by which a pyrolysis oil stream was delivered to a vacuum pipestill to obtain a deasphalted cut of tar and an asphaltenic stream. The asphaltenic stream was further delivered to a coker or a partially oxidizing unit to produce light products such as coker naphtha, or coker gasoil, or syngas. The deasphalted material was further used as a fuel oil or mixed with locally combusted materials to lower soot make. US patent No. US200901944S8A1 describes a process and an apparatus for upgrading steam cracker tar. Accordingly, a heating process was proposed that reduced the yield of tar or pyrolysis oil in steam cracking process. It was further described that resulting heat treated tar can be separated into gasoil, fuel oil and tar streams. US patent No. US20140061100A1 describes a process to reduce asphaltene content in pyrolysis oil stream and to partially recover consumed thermal energy in pyrolysis process by quenching the pyrolysis oil stream. US patent No. US20070163921A1 discloses a method to improve solubility of steam cracked tar, followed by adding improved steam cracked tar to fuel oil. US patent No. US20140061094A1 relates to a hydrotreating process and a hydrotreated product that can be produced by the hydrotreating process of a pyrolysis oil stream, or pyrolysis tar. This hydrotreated product is further used as diluent for heavy fractions in fuel oil. However, hydrotreating process of pyrolysis oil or pyrolysis tar using conventional catalytic hydrotreatment units without removing asphaltene and coke precursors reduces catalyst life cycle due to rapid catalyst deactivation. US patent No. US20130267745A1 describes an integrated process to convert more than 60% of feedstock crude oil to proper feedstock for steam crackers and produced pyrolysis oil is used as feed to a coking unit.
In view of the forgoing, one objective of the present disclosure is to provide an integrated process for increasing olefin production by combining the bottom residues of one or more cracking units, and processing the bottom residues to prepare a suitable feedstock for steam cracking to form light olefins.